Mastering selections in Photoshop: The Lasso Tool

Who’s the master? You’re the master… after you become proficient with selections in Photoshop. 😉 In the last selections tutorial, we demonstrated the Marquee Tools and now it’s time to learn the Lasso Tools.

The Lasso Tool allow you to draw and pinpoint specific areas of a document. If you like drawing with pencil and paper or cutting and pasting objects from a photo, then you will love the Lasso Tool.

Lasso Tool

When you click on the Lasso Tool from the Toolbar, you will see three different tool options:

Lasso

Polygonal Lasso

Magnetic Lasso

Note: you can select the Lasso Tool by pressing L. You can switch between the Lasso, Polygonal and Magnetic Lasso Tool by pressing SHIFT+L.

The Lasso Tool is great to use with a graphic tablet because it is similar to a pencil. Unlike a mouse or track pad, a graphic tablet can give a better flow when drawing and making selections.

With the Lasso Tool, click on your canvas and start drawing a shape. Once you release the mouse button, Photoshop will close the selection between the start and end points. In the image below, the magenta dots symbolize the start and end points where I released the mouse button. As you can see, Photoshop draws a straight line between points to finish my selection.

There are several options that appear under the menu bar when the Lasso Tool is selected. These options are the same as the Marquee Tool:

A great exercise to practice this tool is selecting specific elements from a photo.

For example, I used my graphic tablet to select the horses leg — as you can see, this is not my first rodeo. 😉

It’s possible to use the Lasso Tool for several reasons but I mostly use it to:

grab pieces from other images

draw shapes, like mountains, for matte paintings

In the image below, I used my excellent painter skills and created a background. I then used the Lasso Tool to create a mountain shape:

It’s not fancy but my goal is to show you the workflow. 🙂 Now, we will fill the mountain selection with a linear gradient (white to gray).

After adding texture, painting in some details and playing around with shadows and highlights, I ended up with the image below:

I copied the mountain shape, transformed and scaled it. Finally, I painted a simple boat.

Voilà! Our demonstration is done.

Polygonal Lasso Tool

Activate the Polygonal Lasso Tool and start clicking on your canvas. You will quickly notice that the Polygonal Lasso only draws straight lines between your points. When you press and hold the Shift key you can create 45 degree angles.

To close a selection, you can either hit the Enter key or connect your first point to your last point — you will notice the icon symbol will change to a lasso and small circle once the selection is ready to be closed.

If you want erase a point as you’re making a selection, you can hit the Delete key.

This tool is great for selecting straight objects such as buildings.

The real power of selections is combining different ones. For example, you can use the Lasso Tool to create a selection then use the Polygonal Lasso Tool to subtract from the selection, and the Marquee tool to intersect. Make sure the right selection is selected in the menu bar: add, subtract or intersect to selection.

Magnetic Lasso

This tool is quite different from the other two and can be a little frustrating when you use it for the first time. The Magnetic Lasso detects an object’s edge and automatically snaps alongside it while you are moving near it.

We will take a closer look at the menu bar which has 3 additional options for this tool:

Width – defines how close you want to stay to an edge while tracing it

Contrast – helps you fine tune the detection of the edge

Frequency – defines how many points will be created along the edge

Using a flower image, create a starting point on an outside edge and begin moving carefully along the pedals. You might notice Photoshop doesn’t snap the points exactly where you’d expect. In this case, you can hit the Delete key to remove the previous point(s).

Sometimes, even when you remove a point and try again, Photoshop won’t snap to the correct area. When this happens, you can help Photoshop by laying down points where the edges are blurry or the contrast isn’t high.

Get a better feel for this tool by playing around and increasing the width, contrast and frequency. Personally, I like to keep the frequency somewhere between 10 and 30. The width and contrast depends on the image size and quality, but the default values of 20 pixel wide and 10% contrast are usually fine.

Note: press the Caps Lock key and your cursor will turn from the Magnetic Lasso icon to a circle showing you the width of the edge detection.